<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>hello world</title>
  <script src="./vue.js"></script>
</head>
<body>
<div id="root">
  {{title}}
</div>
<script>
  var app = new Vue({
    el: "#root",
    data: {
      title: 'aa'
    }
  })

  setTimeout(function () {
    app.$data.title = 'bb'
  }, 2000)



</script>
</body>
</html>
